One of the more recent major advances in the art of photographic film development has been the formulation of a class of rapid access film developer systems for use with automated film processors. With a modification in developer formulation, it is known that it is possible to develop films in about 60-90 seconds by using a developer temperature of over 100.degree. F. (38.degree. C). When this capability is combined with the capability of automated film processors to substantially facilitate and shorten film development process steps, a major improvement in the art is realized, one which has been well received by customers and thereby established as a fixed part of the industry landscape. Reformulated, rapid access developers reduce overall film development time to a few minutes from film development process times previously measured in hourly parts.
When the process is artfully carried out, rapid access automated film development rewards the operator with great convenience, reproducibility, less labor, and lower unit cost. The required hands-on skills shift more to routine machine operations and away from those of the skilled artisan. Consequently, tasks such as preparation of critical rapid access developer solutions are configured to be as easy and error-proof to execute as possible. To that end, the industry today uses premeasured single part or double part developer packages containing all of the principal developer, auxiliary developer, additives, sulfite and alkali in the correct proportions required to prepare a developer aqueous solution of a given volume simply by mixing the entire contents of the package with the appropriate amount of water. The two part developer package is distinguished over the single part package primarily by the inclusion of a restrainer or anti-fogging agent in a second package, essentially as a non-aqueous solution. The developer package can be provided as a single or double part depending on whether or not anti-fogging agent is included in the formulation.
With all its advantages, rapid access film processing is troubled by low contrast development in the film. Film processing at elevated temperature to accelerate development is burdened by a tendency to produce some film fogging that reduces contrast and compromises the ability to distinguish half tones in the film. However, the problem can be readily ameliorated and high contrast capability restored by including an anti-fogging agent in the developer formulation. This is the purpose of the two part system as known in the art where the second part contains the requisite anti-fogging agent that provides high contrast capability to the rapid access film development process.
The formulation of rapid access developer into premeasured, solid, single part packages has been accomplished to provide operational reliability and convenience to the industry and to lessen some of the environmental problems associated with liquid waste container disposal when the single part or two part developer is packaged and sold as a concentrated solution. However, the formulation of single part, rapid access solid developer that includes anti-fogging agent is faced with some challenging problems, as described hereinafter. Consequently, rapid access developer that includes anti-fogging compounds are sold as two part, solid/liquid systems where the anti-fogging agent is provided in solution in a separate or second package containing non-aqueous solvent.
Anti-fogging agents are well known in the art. They are typically organic compounds selected from the group of nitrogen heterocyclic compounds; 5-nitroindazole and benzimidazole are representative of the general class. Rapid access developer formulations containing 5-nitroindazole are formulated as two part systems, dictated by the general instability of the compound in alkaline medium with loss of anti-fogging activity and the poor solubility of the compound in water. If solid nitroindazole is incorporated as part of a solid, single part rapid access developer formulation in the prior art, the indazole does not dissolve when added to the make-up water. Typically, it floats to the top of the tank, rendering the working developer solution unusable.
One approach taken by artisans in the field to overcome the problem of the poor solubility of nitroindazole in water and thus allow the formulation of a solid, single part rapid access developer is to substitute novel anti-fogging agents for nitroindazole in the formulation. U.S. Pat. No. 5,141,843 to Ooms, et al. discloses a new class of anti-fogging agents based on derivatives of tetrazole that are stable and water soluble. It is taught that these new anti-fogging agents can be formulated into a single part developer that obviates the need to include nitroindazole in the formulation. As effective as these new agents, or other new agents, may be, it would be desirable to provide a solid, rapid access, single part developer system that includes established and effective anti-fogging agents, particularly nitroindazole. 5-nitroindazole, for instance, is well known and accepted in the art as an anti-fogging agent so that finding a means to successfully include it in a single part, solid, rapid access developer system would represent an acceptable and highly useful contribution to the art.
It is an objective of this invention to provide a solid, high contrast, rapid access developer comprising a readily water soluble, single part composition.
Another objective of the invention is to provide the above readily water soluble, solid, single part, high contrast, rapid access developer composition containing nitroindazole, particularly 5-nitroindazole, as the anti-fogging agent.
Yet a further objective of the present invention is to provide a method for producing the foregoing novel solid, single part, rapid access developer.
A specific goal of the invention is to provide a composition comprising solid, readily water soluble anti-fogging agents or mixtures, particularly solid, readily water soluble 5-nitroindazole compositions, and a method for producing these water soluble compositions.